import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:平方数
 * User: wangxin
 * Date: 2024-08-01
 * Time: 10:50
 */
public class test1 {
    public class Main {
        public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
            // 注意 hasNext 和 hasNextLine 的区别
            long x = in.nextLong();
            long y1 = (long)Math.sqrt(x);
            long y2 = y1 + 1;
            if(Math.abs(y1*y1 - x) < Math.abs(y2*y2-x)){
                System.out.println(y1*y1);
            }else{
                System.out.println(y2*y2);
            }

        }
    }
}
